Not aware of any way to independently or directly control the BLF lamps, unfortunately.
The lamps can be configured to automatically update based on shared-line call activity (shared line) or phone presence activity (BLF). It would theoretically be possible to have an application instantiate some dummy lines (via TAPI/JTAPI and CTI ports) and start/stop 'fake' calls to cause the lamps to light. It might also be possible to configure a BLF lamp for a dummy line, and use the IM&P Presence Web Service API to force a 'fake' phone presence status update for the line (not so sure about this one.)
If someone can discern the actual approach taken by the referenced app, we may be able to speculate more accurately...